Locking means for doctor blades



Nov. 29, 1955 sco T 2,724,999

LOCKING MEANS FOR DOCTOR BLADES Filed May 12, 1952 III INVENTOR HAROLD E.B. SCOTT United States Patent LOCKING MEANS FOR DOCTOR BLADES Harold E. B. Scott, Weybridge, England, assignor to Vickerys Ltd., London, England Application May 12, 1952, Serial No. 287,435

3 Claims. (Cl. 92-74) It is an object of this invention to provide locking means for a doctor blade which will permit edgewise removal of the blade from the holder and which will also permit lengthwise withdrawal of both blade and locking means from the holder, with consequent removal of any accumulated fuzz.

It is a further object of this invention to provide locking means as aforesaid which, in addition, afford a resilient support for the back edge of the blade.

The above and other objects will be made clear from the following detailed description, taken in connection with the annexed drawings, in which:

Figure l is a perspective view, partially in section, showing the improved assembly of blade, holder and locking means; and

Figure 2 is a similar view showing a modified form of locking means.

Doctor blades are used to clean practically every roll in a paper machine and extend the full width of each roll to which they are applied. It has long been established that such blades should be free to flex so as to conform to any inequalities in the surface of the roll. Since the function of the blade is to remove pulp particles from the roll against which the blade bears, there is constantly accumulating a body of pulp or fuzz which at times works into the blade holder and packs in tightly enough to interfere with proper flexing of the blade. When this occurs, edgewise removal of the blade from the holder is extremely difficult and most of the holders now in use will permit only an edgewise removal. The present invention contemplates a locking means which, while permitting edgewise removal of the blade, also permits lengthwise removal of both the blade and the locking means, which removal simultaneously will clean out the slot of the holder and recondit-ion the blade for proper use.

Referring now to Figure 1 there is shown a blade holder having a forward edge 12 bearing on a blade 14. The rear edge 16 of the blade 14 enters a slot 18 in the holder 10. A strip of metal 20, coextensive in length with the blade 14, lies in a slot 22 in the holder 10 and has at intervals along its length pieces of spring metal 24 riveted thereto as shown at 26. These springs 24 normally enter slots 28 formed adjacent the rear edge 16 of the blade 14 and when the springs 24 are engaged with the slots 28 they prohibit edgewise removal of the blade from the holder. If edgewise removal is desired the blade 14 is held stationary and the strip is drawn endwise in the direction of the rivets 26. This action compresses the springs 24 against the ends 30 of the slots 28. The compression pushes the springs 24 down into the plane of the lower surface of the blade 14 which may then be removed edgewise from the holder.

If, due to an accumulation of fuzz, edgewise removal of the blade would be difficult, then both the strip 20 and the blade 14 may be drawn together endwise out of the holder, after which they can be separated, cleaned and restored to position.

Referring now to Figure 2 there is shown a holder 50 and a blade 52 having its rear edge 54 in a slot 56 in the holder 50. A U-shaped strip 58 has secured to its lower leg 60 a series of springs 62 similar to the springs 24 described with reference to Figure 1. The springs 62 protrude through slots 64 in the upper leg 66 of the U-shaped strip and this protrusion is sufficient to enable the springs to enter slots 68 in the blade 52, the engagement being precisely similar to the engagement of springs 24 with the slots 28 of Figure 1. The rear edge 54 of the blade 52 bears on the edge 70 of the upper leg 66 of the U-shaped strip 58. This constitutes a spring and afiords resilient support for the rear edge 54 of the blade 52.

Edgewise withdrawal of the blade is accomplished precisely as has been described with reference to Figure 1. The blade is held still and the strip is moved lengthwise enough to cam the springs 62 out of the slots in the blade while for lengthwise removal the blade 52 and the U- shaped strip 58 are simultaneously withdrawn from the holder.

While specific embodiments of this invention have been described, it is not intended to limit the invention to the precise details disclosed but only as set forth in the subjoined claims.

I claim:

1. A doctor blade assembly for use on paper machines comprising: a rigid, elongated blade holder; an elongated flexible blade; said holder having a groove extending throughout its length and receiving the rear edge of said blade, the width of said groove exceeding the thickness of said blade, said blade having a series of spaced perforations adjacent its rear edge; an elongated relatively rigid blade locking member in said holder and slidable lengthwise of said holder parallel to said groove; a series of mutually independent short springs each secured at only one of its ends to said locking member, said springs being sized and spaced to enter the perforations in said blade to lock the same against edgewise displacement and being curved relative to the plane of the blade so that upon relative lengthwise movement, within said holder, between the blade and the locking member, said springs will be cammed out of said perforations.

2. A doctor blade assembly as set forth in claim 1 in which the locking member is U-shaped in transverse cross-section.

3. A doctor blade assembly as set forth in claim 2 in which the under side of the rear edge of the blade bears on one arm of the U-shaped locking member.

References Cited in the file of this patent UNITED STATES PATENTS 941,566 Fleming Nov. 30, 1909 1,454,055 Klamroth May 8, 1923 1,863,466 Carlson June 14, 1932 1,929,162 Cook Oct. 3, 1933 2,498,213 Ljungquist Feb. 21, 1950 

